Increasingly, implantable medical devices, such as cardiac rhythm management devices, detect a wide range of physiological and/or behavioral data that may be useful to health care providers servicing the individual in which the device is implanted. For example, a cardiac rhythm management device may record information regarding the physical exertion of a patient, the patient's rate of breathing, heart sounds generated by the patient, and so on. Such information may be transmitted from the implanted device to a programmer in a doctor's office, for example. Alternatively, such information may be transmitted to an access point for a wireless network, whereupon the data may be stored in a datastore for later retrieval by a physician or other health care provider. The physician may access the data, using a web browser, for example, to remain updated about the patient's condition.
In such a scheme, it may be important that communication between the implanted medical device and the access point (or other external system, such as a computer, personal digital assistant, or programmer) is confidential and secure. To that end, encryption schemes may be employed to attain the desired security. Thus, before transmission from the implanted device, data is encrypted, and may be decrypted by the appropriate receiving device (and vice versa).